Adaptive Circuit Board Assembly and Flexible PCI Express Bus

ABSTRACT

A system and method for adaptive bus configuration operable to respond to hardware changes and other configuration changes is disclosed. In an embodiment, the computing system includes a circuit assembly having at least one processing resource coupled to a respective set of bus traces, at least one peripheral device socket coupled to a respective set of bus traces, and a bus switch coupled to the bus traces of the processing resource and the bus traces of the peripheral device. The bus switch implements a set of connections between the bus traces of the processing resource and the bus traces of the peripheral device sockets according to an instruction. The instruction may specify an allocation of peripheral device sockets to processing resources based on the number of installed processing resources so that no peripheral device is connected to a bus without an attached processor.

TECHNICAL FIELD

The present disclosure relates generally to computing systems and, moreparticularly, to a printed circuit board for use in a computing systemthat incorporates programmable bus switches in order to supportdifferent configurations of installed devices.

BACKGROUND

While strong demand for storage and processing has translated intosteady sales of ever-more-powerful computing systems, customers havealso become increasingly cost sensitive. Customers won't pay for whatthey don't need, and vendors have responded accordingly. As merely oneexample, enterprise-class storage systems are offered in a wide array ofstorage, processing, and networking configurations. Many customers alsorequest systems that are upgradable over time in order to preserve someof the substantial investment. However, tension arises when customersseek customized hardware and software solutions as a cost-savingmeasure, in part because custom solutions are rarely cheaper to provide.Both vendors and customers carefully balance flexibility against systemcomplexity, which tends to increase support costs and reduce systemreliability.

In particular, vendors have sought opportunities to use a singlecomponent (be it a code fragment, processor, controller, storage device,etc.) in a wide array of products. This, reusability may allow thevendor to leverage economy of scale. In the simplest cases, a componentcan be used in a variety of situations with little or no modification.However, this is not often the case for printed circuit boards (PCBs)and other circuit assemblies. PCBs contain a large number of devices(resistors, capacitors, power circuitry, etc.) and device socketsconnected by conductive traces crossing multiple insulator layers. Inorder to provide optimum performance, the devices and the traces arecarefully laid out based on the installed components. Thus, reusabilitymay take a backseat to reducing trace length and noise. Compounding theproblem, many common protocols used to communicate at the PCB levelrequire direct point-to-point connections rather than more flexibletopologies. Accordingly, for these reasons and others, it would bebeneficial for PCB designs to have the flexibility to support a widerarray of hardware configurations in order to provide more cost-effectivesolutions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a computing system according to someembodiments of the present disclosure.

FIG. 2 is a schematic diagram of a computing system having a flexiblebus architecture according to some embodiments of the presentdisclosure.

FIG. 3 is a flow diagram of a method of assigning peripheral devices toa bus according to some embodiments of the present disclosure.

FIG. 4 is a diagram of an intermediate bus configuration file accordingto some embodiments of the present disclosure.

FIG. 5 is a diagram of a configuration file according to someembodiments of the present disclosure.

FIG. 6 is a perspective view of a portion of computing system having aflexible bus architecture in an assembled form according to someembodiments of the present disclosure.

DETAILED DESCRIPTION

In the following description, specific details are set forth describingsome embodiments consistent with the present disclosure. It will beapparent, however, to one skilled in the art that some embodiments maybe practiced without some or all of these specific details. The specificembodiments disclosed herein are meant to be illustrative but notlimiting. One skilled in the art may realize other elements that,although not specifically described here, are within the scope and thespirit of this disclosure. In addition, to avoid unnecessary repetition,one or more features shown and described in association with oneembodiment may be incorporated into other embodiments unlessspecifically described otherwise or if the one or more features wouldmake an embodiment non-functional.

Various embodiments of the present disclosure provide a circuit assemblythat can be easily reconfigured based on the installed hardware. In oneexample, the circuit assembly includes a number of reconfigurablePeripheral Component Interconnect Express (PCI Express) bus switchesthat can be programmed to connect PCI Express peripherals to one ofvarious processors based on which of the processors are installed.Because PCI Express is a point-to-point protocol, connecting a PCIExpress peripheral to an empty processor socket may leave the peripheralinaccessible. To avoid this, an exemplary PCI Express switch isprogrammed to connect peripherals only to those processors that areinstalled. Because of the switching capability, the same circuitassembly can be used with varying numbers of processors.

The connections made by the switches can also be tailored to theperipheral devices installed in the system. In one example, the switchor switches are programmed to ensure that redundant peripheral devicesare not connected to common hardware such as a common bus or a commonprocessor to avoid a single point of failure disabling all of theredundant devices. In some examples, the switches ensure that eachconnected peripheral device has some minimum amount of a communicationresource (e.g., a minimum number of PCI Express lanes). After theminimum has been met, any leftover amount of the communication resourcemay be allocated according to priorities assigned to the particularperipherals. The switches may also be programmed to account for certainconnections that are fixed and should not be changed. The flexibilityprovided by the programmable switches allows the circuit assembly to beused throughout multiple product lines without substantial changes tothe underlying hardware.

Referring first to FIG. 1, illustrated is a schematic diagram of acomputing system 100 according to some embodiments of the presentdisclosure. In the example of FIG. 1, the computing system 100 includesa number of different computing elements in communication with eachother via a set of communication buses. The communication buses mayconnect any number of computing elements and may conform to any suitablehardware and/or software protocol. For example in one embodiment, buses102A and 102B are characteristic of PCI Express buses. As described inmore detail below, due to the topology of these buses 102A and 102B, itis possible for some computing elements to become unreachable if otherelements are not available or not installed. Thus, the computing system100 of FIG. 1 may support only a limited number of hardwareconfigurations.

The computing system 100 will now be described in more detail andincludes one or more processing resources 104, of which two (104A and104B) are shown. Processing resources 104A and 104B may each include oneor more microcontrollers, Central Processing Units (CPUs),Application-Specific Integrated Circuits (ASICs), Programmable LogicDevices (PLDs), and/or other suitable processing resources operable toperform programmed computing instructions. In some embodiments,processing resources 104A and 104B share a single package, such asdiscrete cores of the same processor. In some embodiments, processingresources 104A and 104B are discrete devices. For example, processingresource 104 may be a first processor chip and processing resource 104may be a second processor chip. In further examples, processingresources 104A and 104B each include multiple devices and may bemulti-processor clusters. The processing resources 104 may be coupled tothe remainder of the computing system 100 via one or more processorsockets 106. Sockets 106 include any type of slot, connector, orconnector array that provides a connection between an installedcomponent and the system 100 and may include a mechanism for easilycoupling and uncoupling the installed component. The computing system100 may include empty sockets 106 and may function without every socket106 populated.

In the illustrated embodiment, the processing resources 104A and 104Bcommunicate with each other via an inter-processor bus 108 such as aQuick Path Interconnect (QPI) bus from Intel Corporation, of SantaClara, Calif. To support this bus 108, each processing resource 104 mayinclude an inter-processor bus controller 110 operable to send andreceive data transactions across the bus 108. Processing resources 104Aand 104B may also include a memory controller 112 coupled to one or morepools of memory 114, such as random access memory (RAM). A pool ofmemory 114 may be dedicated to a particular processing resource 104 orshared between them.

In addition to the processing resources 104, the exemplary computingsystem 100 also includes a number of peripheral devices 116 (includingperipheral device 116A) in communication with the processing resources104. Similar to the processing resources 104, the peripheral devices 116may be coupled to the remainder of the computing system 100 via one ormore peripheral sockets 118. Sockets 118 include any type of slot,connector, or connector array that provides a connection between aninstalled component and the system 100 and may include a mechanism foreasily coupling and uncoupling the installed component. The computingsystem 100 may include empty sockets 118 and may function without everysocket 118 populated.

The peripheral devices 116 may include any type of computing element.For example, a peripheral device 116 may include a graphics processingunit (GPU) or other co-processor. In some examples, a peripheral device116 includes a networking controller such as an Ethernet controller, awireless (IEEE 802.11 or other suitable standard) controller, or anyother suitable wired or wireless communication controller. In someexamples, a peripheral device 116 includes a storage interfacecontroller such as a Serial Attached SCSI (SAS), SATA, iSCSI, FibreChannel, Fibre Channel over Ethernet (FCoE), eSATA, and/or PATAcontroller. In some examples, the peripheral devices 116 includeperipheral controllers such as USB controllers and/or FireWirecontrollers. Some storage devices (e.g., solid-state drives (SSDs)and/or hard disk drives (HDDs)) connect directly to a bus and aresuitable peripheral devices 116.

In the illustrated embodiment, the peripheral devices 116 are coupled tothe processing resources 104A and 104B by two different buses, bus 102Aand bus 102B, although the computing system 100 may include many morebuses. Accordingly, processing resources 104A and 104B may each includea peripheral bus controller 114 for use in communicating with therespective bus. In embodiments where buses 102A and 102B are PCI Expressbuses, the respective peripheral bus controller 114 may be referred toas a root complex.

Bus 102A and bus 102B are separate and independent such that theperipheral devices 116 and processing resource 104 coupled to bus 102Ado not directly communicate with those of bus 102B. In one typicalexample, bus 102A and bus 102B are PCI Express buses, although furtherembodiments incorporate other bus types. PCI Express is a serialpoint-to-point interconnect that connects two devices via a link. PCIExpress links are asymmetrical in that an upstream device, sometimesreferred to as a root device or root complex (e.g., processing resource104A or 104B) initiates communication with a downstream device, referredto as an endpoint (e.g., peripheral devices 116). While a root complexmay be coupled to multiple downstream devices, PCI Express may notsupport a downstream device coupled to more than one root complex.Accordingly, in the illustrated embodiment, buses 102A and 102B areseparate and independent with one bus per root complex (and in turn onebus per processing resource 104). Of course, it is understood that thisis only one of many examples of independent buses within a storagesystem 100.

Because of the separate and independent nature of the buses, if the rootdevice (e.g., a processing resource 104) fails or is not installed, theperipheral devices 116 on the bus may be unreachable. For example, ifprocessing resource 104B were not installed, the associated peripheraldevices 116, including peripheral device 116A, may not be accessible tothe remaining processing resource 104A. Thus, it would be beneficial ifthe connections of bus 102A and bus 102B could be changed based on thepresence of the processing resource 104B so that the same componentscould be used in both system configurations.

FIG. 2 is a schematic diagram of a computing system 200 having aflexible bus architecture according to some embodiments of the presentdisclosure. In many aspects, the computing system 200 includescomponents similar to those described in FIG. 1. For example, thecomputing system 200 includes processing resources 104A and 104B,sockets 106, peripheral devices 116, and peripheral sockets 118substantially similar to those of FIG. 1.

The computing system 200 also includes one or more bus switches 202.Switch 202 is operable to connect the processing resources 104A and 104Bto the peripheral devices 116 and includes upstream ports connected tothe processing resources 104 and downstream ports connected to theperipheral devices 116. The number of ports has been reduced forclarity, although the switch 202 may include any combination of upstreamports and downstream ports. In some examples, switch 202 is apacket-based switch where a field of a data packet determines itsdestination. One advantage of packet-based switching is that many typesof packet switches can route data from any source to any destinationregardless of which bus or buses the devices are on. However, somecommunication protocols (e.g., PCI Express) do not supportpacket-switching, opting to trade flexibility for improved datathroughput. In these cases, the switch 202 may create one or moreseparate and independent point-to-point buses coupling peripheraldevices 116 to a processing resource 104. The assignment of a peripheraldevice 116 to a bus and thereby assigning it to a processing resource104 may be carried out by programming the switch 202 to connect thevarious elements. The selected assignment may be based on whichprocessing resources 104 are installed and active, which peripheraldevices 116 are installed, performance considerations, peripheral devicepriorities, and/or other system considerations.

An example of this allocation process is described with reference toFIGS. 2-5. FIG. 3 is a flow diagram of a method 300 of assigningperipheral devices to a bus according to some embodiments of the presentdisclosure. It is understood that additional steps can be providedbefore, during, and after the steps of method 300, and that some of thesteps described can be replaced or eliminated for other embodiments ofthe method 300. FIG. 4 is a diagram of an intermediate bus configurationfile 400 according to some embodiments of the present disclosure. FIG. 5is a diagram of a configuration file 500 according to some embodimentsof the present disclosure.

Referring to block 302 of FIG. 3 and to FIG. 2, the numbers of variousbus-limiting devices installed and active in the computing system 200are determined. Bus-limiting devices may include processing resources104, peripheral devices 116, bus wires, switch 202 ports, and/or othercommunication elements. For example, in PCI Express-based embodiment,each root complex is a bus-limiting device because each bus may have oneand only one root complex. In the embodiments of FIG. 2, the rootcomplexes are integrated into the processing resources 104A and 104B.Accordingly, in these examples, determining how many bus-limitingdevices are installed includes determining how many processing resources104 are installed. In one such example, the computing system 200 maypoll the processor sockets 106 to determine how many processingresources 104 are installed and which sockets 118 they are installed in.Additionally or in the alternative, other components, such as the switch202, are bus-limiting devices. For example, a switch 202 may have alimited number of upstream ports (three in the example of FIG. 2), whichmay define a limit on the number of buses that may be created.

The computing system 200 may determine for itself how many bus-limitingdevices are installed. However, there are also advantages to assessingthe installed bus-limiting devices before the computing system 200 isoperational or even before the system 200 is fully assembled. Thus, invarious embodiments, the determination is made in part by a computingsystem other than computing system 200, such as a manufacturing system204 used in the design and/or assembly of the computing system 200.Employing a separate system such as the manufacturing system 204 mayavoid the need to add components to the computing system 200 to supporta partial boot of the system 200. Similarly, in some embodiments, thedetermination is made in part by a technician. This may be useful whencomponents (e.g., the switch 202) cannot be polled electronically.

Referring to block 304 of FIG. 3 and to FIG. 2, a maximum number ofbuses is determined based on how many bus-limiting devices are installedin the computing system 200. In the embodiments of FIG. 2, thedetermining entity (one or more of the computing system 200, themanufacturing system 204, and/or the technician) recognizes that twoinstalled processing resources 104A and 104B allow for, at most, two PCIExpress buses even though the switch 202 and the processor sockets 106support up to three. In another exemplary embodiment, the determiningentity determines that a system 200 with a single root complex will onlysupport a single PCI Express bus.

Referring to block 306 of FIG. 3, various bus performance criteria ofthe computing system 200 are assessed. The assessment may be performedby the computing system 200, by another system such as the manufacturingsystem 204, and/or by a technician and may include identifying thepossible communication links available between devices as well asperformance metrics such as bandwidth, latency, and/or overhead. Forexample, PCI Express devices typically communicate using sets ofparallel conductors referred to as lanes. Each lane may transmit one bitper cycle. By connecting multiple lanes in parallel between two devices,multiple bits per cycle may be transmitted. Common configurationsinclude x1, x2, x4, x12, x16, and x32 connections. The maximumattainable bandwidth between any two devices may be limited if there arenot enough conductors running between the devices. For example, two x16devices connected via an x8 bus may not operate at their full potential.Accordingly, to determine the maximum performance attainable from a bus,attributes (e.g., protocol, bandwidth, communication medium, number ofconductors, etc.) of the processing resources 104, of the processorsockets 106, of the device sockets 118, of the switch 202, of theconnections between these elements, and/or any other attribute of thecomputing system 200 may be considered. Other relevant performancecriteria may include the communication medium and the communicationprotocol because, while a bus may utilize any suitable communicationmedium and any suitable communication protocol, the particular choice ofmedium and protocol may dramatically affect how the computing system 200should be configured in order to maximize performance.

Referring to block 308 of FIG. 3 and to FIG. 4, an intermediate busconfiguration file 400 may be provided to the computing system 200. Asdiscussed above, the determinations of blocks 302-306 may be made by thecomputing system 200, another computing system, and/or a technician.Subsequent determinations based on installed peripheral devices 116 mayalso be made by the computing system 200, another computing system,and/or a technician. For a variety of reasons, in some embodiments, itis advantageous for an entity other than computing system 200 todetermine the number of installed bus-limiting devices, to determine themaximum number of buses, and to assess the bus performance attributes.For example, the bus-limiting devices and the bus architecture maychange infrequently compared to the peripheral devices 116, which may beadded and removed far more often. Furthermore, some of the bus-limitingdevices such as the switch 202 may not support polling and thus may bedifficult to assess by the computing system 200 itself. In addition,because processing resources are often used earlier in the boot sequencethan the peripheral devices 116, configuring the computing system 200 todetect these elements may entail more modifications to the system 200.To alleviate these issues, some or all of blocks 302-306 may beperformed by another entity. The other entity can provide information inthe form of the intermediate bus configuration file 400 to the computingsystem 200 to simplify the bus configuration tasks performed by thesystem 200 itself.

An exemplary intermediate bus configuration file 400 is shown in FIG. 4.The exemplary intermediate bus configuration file 400 containsinformation determined in one or more of blocks 302-306. In one example,the intermediate bus configuration file 400 contains an entry 402representing the maximum number of buses supported in the current system200 configuration. In a further example, the intermediate busconfiguration file 400 contains an entry 404 representing the number ofprocessing resources 104 installed in the computing system 200 and maycorrelate the processing resources 104 to the processor sockets 106 inwhich they are installed. Additionally or in the alternative, theintermediate bus configuration file 400 may contain an entry 406correlating the installed processing resources 104 to the ports of aswitch 202 (e.g., PCI Express upstream ports) to which they areconnected. Some entries of the intermediate bus configuration file 400may also record a communication performance attribute of an element ofthe computing system 200. For example, entries 408 record the number ofPCI Express lanes supported by various elements of the computing system200. Exemplary entries 410 record the number of PCI Express lanesavailable for particular ports of a switch 202. Of course, theseexamples are not intended to be limiting, and the intermediate busconfiguration file 400 may include any combination of these and othersuitable entries. The intermediate bus configuration file 400 berepresented in any suitable format, and in various embodiments isrepresented as a linked list, a tree, a table such as a hash table, anassociative array, a state table, a flat file, a relational database,and/or other memory structure.

Referring to block 310 of FIG. 3 and referring back to FIG. 2, theperipheral devices 116 installed in the computing system 200 areidentified. The identification may be performed by the computing system200, by another computing system, and/or by a technician. In someembodiments, this includes identifying the type of peripheral device 116installed (e.g., graphics processing unit, co-processor, networkingcontroller, peripheral controller, storage interface controller, storagedevice, etc.). In some embodiments, this includes identifying a minimum,average, expected, and/or peak performance metric of the peripheraldevice 116. For example, in one such embodiment, the maximum number ofPCI Express lanes supported by a peripheral device 116 is identified. Insome embodiments, identifying the peripheral devices 116 includesidentifying those peripheral devices 116 designated to operate inparallel as redundant devices such as redundant storage controllers. Insome embodiments, identifying the peripheral devices 116 includesidentifying unpopulated peripheral sockets 118 so that bus resources arenot wasted on an empty socket.

Referring to block 312 of FIG. 3, an allocation of peripheral devices116 to buses is determined. Any of the system aspects determined inblocks 302-310 may be considered in determining the allocation. To doso, the determining entity (e.g., the computing system 200, anothercomputing system such as the manufacturing system 204, and/or atechnician) may consider any analysis performed by the entity, analysisperformed by other entities such as that recorded in the intermediatebus configuration file 400, and/or any other configuration orperformance data. The determination may also consider various rules suchas priority rules and/or minimum specified resource rules governing theperipheral devices 116.

Various exemplary embodiments will now be described. While any of theconsiderations described in the various exemplary embodiments may becombined with any other considerations, in the interest of brevity, onlya limited number of combinations will be described. In one exemplaryembodiment, the allocation is determined so that each peripheral device116 is connected to at least one processing resource 104 by at least onebus. In one exemplary embodiment, the allocation is determined so thateach peripheral device 116 is connected to only one processing resource104 by only one bus. In one exemplary embodiment, the allocation isdetermined so that peripheral devices 116 of similar types are dividedequally between the processing resources 104. In one exemplaryembodiment, the allocation is determined so that redundant peripheraldevices 116 are not assigned to a common bus, switch 202, and/orprocessing resource 104. In one exemplary embodiment, the allocation isdetermined so that each processing resource 104 is coupled to at leastone peripheral device 116 of a given type (e.g., GPUs, storagecontrollers, storage devices, etc.). In one exemplary embodiment, theallocation is determined so that each peripheral device 116 is allocatedat least a minimum amount of an available communication resource (e.g.,at least a x1 link, at least a x2 link, at least a x4 link, etc.). Inone exemplary embodiment, the allocation is determined so that highpriority peripheral devices 116 (e.g., GPUs, storage controllers,storage devices, etc.) are allocated the remainder of an availablecommunication resource after a minimum has been satisfied among theperipheral devices 116. In one exemplary embodiment, the allocation isdetermined so that a particular peripheral device 116 is the onlyperipheral device 116 coupled to a particular bus. In one exemplaryembodiment, the allocation is determined to account for certainconnections, buses, and/or links that are fixed and cannot be changed.In one exemplary embodiment, the allocation is determined so thatcommunication resources are directed away peripheral sockets 118 that donot have an attached peripheral device 116 and redistributed topopulated sockets 118.

Referring to block 314 of FIG. 3 and to FIG. 5, a configuration file 500is created based on the allocation of peripheral devices 116 to buses.The configuration file 500 may be created by the computing system 200 orprovided to the computing system by another entity. The configurationfile 500 includes an instruction for one or more switches 202 of thecomputing system 200 to implement the determined allocation ofperipheral devices 116 to buses and processing resources 104. Asdescribed above, the switches 202 are programmable to implement variousbus configurations, and the particular bus configuration is selected bythe configuration file 500.

FIG. 5 illustrates an exemplary configuration file 500, although it isunderstood that the configuration file 500 may take any other suitableform and may be represented in any suitable format including an FPGA(Field Programmable Gate Array) table, a PLD (Programmable Logic Device)configuration file, a table such as a hash table, an associative array,a state table, a linked list, a tree, a flat file, a relationaldatabase, and/or other memory structure. In an embodiment, theconfiguration file 500 for a 4-way x32 switch 202 includes 32 entries502 for each upstream port. Each entry 502 correlates a link of theupstream port to a link of a downstream port based on the allocation ofblock 314. Referring to block 316, when the configuration file 500 isloaded into the switch 202, the upstream ports are connected to thedownstream ports based on the entries 502 of the configuration file 500to form the specified bus connections. In this way, the communicationbuses of the computing system 200 can be configured based on theinstalled elements.

An exemplary implementation of the computing system 200 will now bedescribed. Whereas FIG. 2 is a schematic diagram of the computing system200, FIG. 6 is a perspective view of a portion of the computing system200 in an assembled form according to some embodiments of the presentdisclosure. FIG. 6 shows the computing elements arranged on a circuitboard assembly 600, such as a motherboard, a daughter board, anexpansion card, and/or another circuit assembly. The circuit boardassembly 600 physically supports the elements and provides communicativeconnections between them. In many embodiments, the circuit boardassembly 600 is made up of a number of alternating insulating andconductive layers. The insulating layers 602 provide rigidity anddurability and typically contain an insulating material combined with anepoxy to create a laminate sheet. Typical materials includeglass-reinforced epoxy laminate. The conductive layers 604 containconductive traces 606 that connect the various elements disposed on thecircuit board assembly 600. Based on the application, conductive traces606 may include any conductive material including copper, tin, silver,gold, other metals or metal alloys, and/or non-metallic conductors. Theconductive traces 606 may be formed on or bonded to the insulatinglayers 602 or may be formed on a backing material. Conductive traces 606on different conductive layers may entail creating openings in theinsulating layers 602. The openings are filled with vertical conductivesegments to create via structures between the traces 606 of thedifferent conductive layers.

The circuit board assembly 600 includes one or more processing resources104 (e.g., processing resources 104A and 104B) coupled to the circuitboard assembly 600. In some embodiments, the processing resources 104are inserted into a processor socket 106 that is soldered or otherwiseaffixed to the circuit board assembly 600. In alternate embodiments, theprocessing resources are soldered or otherwise affixed to the circuitboard assembly 600 directly. The circuit board assembly 600 may alsoinclude memory and/or memory sockets disposed thereupon and may includetraces 606 coupling the memory to one or more of the processingresources.

Circuit board assembly 600 may also include one or more peripheraldevices 116 and/or peripheral sockets 118 for coupling peripheraldevices 116. Referring to FIG. 6, some peripheral devices 116 arerepresented by translucent shapes to avoid hiding other elements.Exemplary peripheral devices 116 may include but are not limited tographics processing units, co-processors, networking controllers,peripheral controllers, storage interface controllers, and/or storagedevices. In order to communicatively couple the peripheral devices 116to the processing resources 104, the circuit board assembly 600 mayinclude conductive traces 606 forming one or more communication buses.In more detail, the conductive traces 606 may connect the peripheraldevices 116 and the processing resources to one or more switches 202. Inturn, the switches 202 determine how the peripheral devices 116 map tothe processing resources 104. In some embodiments, the circuit boardassembly 600 includes conductive traces 606 coupled to a commandinterface or other programming port of a switch 202 over which theswitch 202 may be programmed as described in the context of FIGS. 2-5.

Embodiments of the present disclosure can take the form of a computerprogram product accessible from a tangible computer-usable orcomputer-readable medium providing program code for use by or inconnection with a computer or any instruction execution system. For thepurposes of this description, a tangible computer-usable orcomputer-readable medium can be any apparatus that can store the programfor use by or in connection with the instruction execution system,apparatus, or device. The medium can be an electronic, magnetic,optical, electromagnetic, infrared, or a semiconductor system (orapparatus or device). In some embodiments, one or more processors 110 ofthe storage system 102 execute code to implement the actions describedabove.

Accordingly, a system and method for adaptive bus configuration thataccounts for installed hardware is provided. In some exemplaryembodiments, the computing system comprises a circuit assembly havingcoupled to and disposed thereupon: at least one processing resource, atleast one peripheral device socket, and a bus switch. Each of the atleast one processing resource is coupled to a respective set of bustraces, and each of the at least one peripheral device socket is coupledto a respective set of bus traces. Accordingly, the bus switch iscoupled to each set of bus traces of the at least one processingresource and to each set of bus traces of the at least one peripheraldevice socket. The bus switch is operable to receive an instruction and,based on the instruction, to implement a set of connections between eachset of bus traces of the at least one processing resource and each setof bus traces of the at least one peripheral device socket. In one suchembodiment, the bus switch is operable to communicatively couple the atleast one peripheral device socket to the at least one processingresource such that each peripheral device of the computing system iscommunication with at least one of the at least one processing resource.In one such embodiment, the computing system further includes at leastone root complex associated with the at least one processing resourceand the bus switch includes a Peripheral Component Interconnect Express(PCI Express) bus switch. The bus switch is operable to communicativelycouple the at least one peripheral device socket to the at least oneprocessing resource such that each peripheral device of the computingsystem is coupled to at least one of the at least one root complex via aPCI Express bus.

In further exemplary embodiments, the method of configuring a computingsystem includes determining a count of installed processing resources ofthe computing system. Based on the count of installed processingresources, a configuration file is generated that specifies a deviceassignment of a peripheral device of the computing system to a bus ofthe computing system associated with an installed processing resource.The configuration file is provided to a switch in communication with theperipheral device and the bus. The configuration file configures theswitch to implement the device assignment and to communicatively couplethe peripheral device to the installed processing resource via the bus.In one such embodiment, the generating of the configuration fileincludes, based on the count of installed processing resources,determining the device assignment such that each peripheral device ofthe computing system is coupled to at least one of the installedprocessing resources. In one such embodiment, the generating of theconfiguration file also includes determining the device assignment suchthat each peripheral device of the computing system is allocated aminimum communication resource.

In yet further exemplary embodiments, the apparatus comprises anon-transitory, tangible computer readable storage medium storing acomputer program, wherein the computer program has instructions. Whenexecuted by a computer processor, the instructions carry out:determining a processor count of a computing system having one or moreinstalled processors; allocating a set of peripheral device sockets tothe one or more installed processors based on the determined processorcount such that each socket of the set of peripheral device sockets iscommunicatively coupled to at least one of the one or more installedprocessors; generating a switch instruction for implementing theallocation; and providing the switch instruction to a switch of thecomputing system and thereby coupling the set of peripheral devicesockets to the one or more installed processors. In some suchembodiments, the apparatus comprises further instructions that carry outallocating the set of peripheral device sockets further based on aperipheral device priority.

Although illustrative embodiments have been shown and described, a widerange of modification, change and substitution is contemplated in theforegoing disclosure and in some instances, some features of theembodiments may be employed without a corresponding use of otherfeatures. One of ordinary skill in the art would recognize manyvariations, alternatives, and modifications. Thus, the scope of theinvention should be limited only by the following claims, and it isappropriate that the claims be construed broadly and in a mannerconsistent with the scope of the embodiments disclosed herein.

What is claimed is:
 1. A computing system comprising: a circuit assemblyhaving coupled to and disposed thereupon: at least one processingresource, wherein each of the at least one processing resource iscoupled to a respective set of bus traces; at least one peripheraldevice socket operable to receive a peripheral device, wherein each ofthe at least one peripheral device socket is coupled to a respective setof bus traces; and a bus switch coupled to each set of bus traces of theat least one processing resource and to each set of bus traces of the atleast one peripheral device socket, wherein the bus switch is operableto receive an instruction and, based on the instruction, to implement aset of connections between each set of bus traces of the at least oneprocessing resource and each set of bus traces of the at least oneperipheral device socket.
 2. The computing system of claim 1, whereinthe bus switch is operable to communicatively couple the at least oneperipheral device socket to the at least one processing resource suchthat each peripheral device of the computing system is communicationwith at least one of the at least one processing resource.
 3. Thecomputing system of claim 1 further comprising: at least one rootcomplex associated with the at least one processing resource, whereinthe bus switch includes a Peripheral Component Interconnect Express (PCIExpress) bus switch, and wherein the bus switch is operable tocommunicatively couple the at least one peripheral device socket to theat least one processing resource such that each peripheral device of thecomputing system is in communication with at least one of the at leastone root complex via a PCI Express bus.
 4. The computing system of claim1, wherein the computing system is operable to determine how manyprocessing resources are installed in the computing system and togenerate the instruction based on how many processing resources areinstalled.
 5. The computing system of claim 1, wherein the computingsystem is operable to: receive a configuration file specifying at leastone of: a count of installed processing resources, a maximum number ofsupported buses, or a bus performance criterion; and generate theinstruction based on the received configuration file.
 6. The computingsystem of claim 1, wherein the instruction contains an allocation of theat least one peripheral device socket to the at least one processingresource based on a priority of a peripheral device installed in one ofthe at least one peripheral device socket.
 7. The computing system ofclaim 1, wherein the instruction contains an allocation of the at leastone peripheral device sockets to the at least one processing resourcebased on a minimum connection resource rule.
 8. The computing system ofclaim 7, wherein the allocation is further based on an amount of aconnection resource remaining after satisfying the minimum connectionresource rule.
 9. A method of configuring a computing system, the methodcomprising: determining a count of installed processing resources of thecomputing system; generating a configuration file based on the count ofinstalled processing resources, wherein the configuration file specifiesa device assignment of a peripheral device of the computing system to abus of the computing system associated with an installed processingresource; and providing the configuration file to a switch incommunication with the peripheral device and the bus, whereby theproviding of the configuration file configures the switch to implementthe device assignment and to communicatively couple the peripheraldevice to the installed processing resource via the bus.
 10. The methodof claim 9, wherein the generating of the configuration file includes:based on the count of installed processing resources, determining thedevice assignment such that each peripheral device of the computingsystem is coupled to at least one of the installed processing resources.11. The method of claim 9, wherein the generating of the configurationfile includes: determining the device assignment such that eachperipheral device of the computing system is allocated a minimumcommunication resource.
 12. The method of claim 9, wherein thegenerating of the configuration file includes: determining the deviceassignment based on a priority of the peripheral device.
 13. The methodof claim 9, wherein the generating of the configuration file includes:determining the device assignment such that two redundant peripheraldevices do not share a common bus.
 14. The method of claim 9, whereinthe generating of the configuration file includes: determining thedevice assignment such that the device assignment allocates busresources away from an unpopulated peripheral socket and to a populatedperipheral socket.
 15. The method of claim 9, wherein the switchincludes a Peripheral Component Interconnect Express (PCI Express)switch, and wherein the configuring of the switch includescommunicatively coupling the peripheral device to the installedprocessing resource via a PCI Express bus.
 16. An apparatus comprising:a non-transitory, tangible computer readable storage medium storing acomputer program, wherein the computer program has instructions that,when executed by a computer processor, carry out: determining aprocessor count of a computing system having one or more installedprocessors; allocating a set of peripheral device sockets to the one ormore installed processors based on the determined processor count suchthat each socket of the set of peripheral device sockets iscommunicatively coupled to at least one of the one or more installedprocessors; generating a switch instruction for implementing theallocation; and providing the switch instruction to a switch of thecomputing system and thereby coupling the set of peripheral devicesockets to the one or more installed processors according to theallocation.
 17. The apparatus of claim 16 comprising furtherinstructions that carry out: allocating the set of peripheral devicesockets further based on a peripheral device priority associated with aperipheral device installed in a socket of the set of peripheral devicesockets.
 18. The apparatus of claim 16 comprising further instructionsthat carry out: allocating the set of peripheral device sockets furtherbased on a minimum resource rule.
 19. The apparatus of claim 16comprising further instructions that carry out: allocating the set ofperipheral device sockets such that redundant peripheral devicesinstalled in the set of peripheral device sockets do not share a givencommunication element.
 20. The apparatus of claim 16 comprising furtherinstructions that carry out: allocating the set of peripheral devicesockets to account for unpopulated peripheral connections.